Photographic developing compositions



United States Patent 3,380,829 PHGTOGRAPHIC DEVELOPIYG *CGMPQSTEIONS Leslie Frederick Alfred Mason and Abraham Mark Sinciair, Ilford, England, assignors t0 Ilford Limited, Ilford, England, a British company No Drawing. Filed Aug. 24, 1964, Ser. No. 391,740 Claims. (Cl. 96-66) ABSTRACT OF THE DKSCLOSURE There is provided a photographic developer composition with a hardening agent for gelatin therein and method of developing and hardening the same. The composition comprises a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from hydroxides and carbonates of alkali metals, 2,3- dihydroxy-l,4-dioxane (a hardener for gelatin) and a source of borate ions. It has been found that the dioxane hardener will decrease in effectiveness with age, and that such a decrease of effectiveness may be prevented or at least minimized by including in the developer borate ions. As a further feature, 1,4-diketone or diacetyl is included in the composition to enhance the hardening effect of the dioxane.

This invention relates to photographic developing compositions and more particularly to developing compositions which are intended for the development of gelatino silver halide emulsions and contain a hardening for the gelatin.

In British Patent No. 805,120 there is claimed a method of hardening an aqueous gelatin composition which comprises incorporating therein, 2,3 dihydroxy-1,4-dioxane. The method of use there described is to mix the gelatin, while in the form of an aqueous solution, with a small proportion of 2,3-dihydroxy-l,4-dioxane.

It has been found that this compound will exert a useful hardening action of a gelatino silver halide emulsion if included in a developer solution employed for the development of such an emulsion. In the usual types of developer formulation, however, which contain alkali hydroxides or carbonates, the hardening action of the compound tends to fall off with the increasing age of the developer. It has now been found that this loss of hardening activity can be prevented or minimised by including a small proportion of borate ions in the developer. Whilst the reason for this is not known with certainty it is believed that it may be due to the formation of a complex between the 2,3-dihydroxy'1,4-dioxane and the borate of the type known to be formed between borates and compounds having vicinal hydroxy groups.

According to a first feature of the present invention, therefore, a photographic developer composition comprises a developing agent for a silver halide photographic emulsion, an alkali hydroxide and/or carbonate, 2,3-dihydrox -l,4-dioxane and a source of borate ions. The developer compositions may contain additionally any of the ingredients commonly present in photographic developers, e.g. restrainers, anti-fogging agents and/or sulphites.

The photographic developer may be any such substance known per so from the literature and includes combinations of developing substances such as those which provide a synergistic effect, e.g. a combination of metol (pmethylaminophenol) and hydroquinone. Preferably, however, there is employed as developing agent a combination of a 3-pyrazolidone, e.g. l-phenyl-3-pyrazolidone or analogous compounds and derivatives thereof, e.g. the 4-methyl or dimethyl derivatives together with another developer with which it affords a synergistic or so-called superadditive effect, e.g. hydroquinone, gentisic acid or ascorbic acid.

The alkali hydroxide or carbonate may be the hydroxide or carbonate of any of the alkali metals, but is preferably a potassium or sodium compound.

The source of borate ions is preferably borax (sodium borate), but may be boric acid or any other water-soluble salt of boric acid.

A suitable restrainer is potassium bromide. Suitable anti-fogging agents are benzotriazole, 6-nitro-benzimidazole or l-phenyl-S-mercapto tetrazole and many other such compounds are known per se. The sulphite, when present, will usually be an alkali metal sulphite or metabisulphite, preferably the sodium or potassium salts.

It is found that, for optimum results the 2,3-dihydroxy- 1,4-dioxane and the source of borate ions should preferably be present in substantially equimolar proportions. Using borax as the source of borate ions the optimum weight ration is accordingly 1 part of borax to about 0.32 part of 2,3-dihydroxy-1,4-dioxaue. Instead of borax any other soluble borate, or boric acid, may be employed as the source of borate ions in equivalent amount.

It has further been found that it is possible to enhance the hardening effect of 2,3-dihydroxy-1,4-dioxane by including a proportion of other hardening agents in the developer solution.

According to another feature of the present invention there is provided a photographic developer composition comprising a developing agent for a silver halide photographic emulsion, an alkali hydroxide and/or carbonate, 2,3-dihydroxy-l,4-dioxane and a source of borate ions, together with at least one of the following hardening agents:-diacetyl and a 1,4-diketone which possesses a hardening action on gelatin.

In the preferred embodiment of the invention the photographic developer composition comprises a developing agent for a silver halide photographic emulsion, an alkali hydroxide and/or carbonate, 2,3-dihydroxy-l,4-dioxane and a source of borate ions, together with diacetyl and a 1,4-diketone which possesses a hardening action on gelatin.

A 1,4-diketone which has been found useful for the invention is acetonyl acetone.

The preferred quantities of hardening agents per litre of developing solution are 2,3-dihydroxy-1,4-dioxane 0.64 to 20 g., diacetyl l to 20 g. and 1,4-diketone 1 to 20 g.

The following example will serve to illustrate the invention and its embodiments:

Example G. A developer was formulated as follows:

Potassium sulphite 44 Sodium sulphite 35-65 Hydroquinone l5 1-phenyl-3-pyrazolidone 0.24 Potassium bromide 8.5

Hardening agents:

(A) 2,3-dihydroxy-l,4-dioxane 0.64-20 Borax 264 (B) Diacetyl 1-20 (C) Diacetonyl acetone 1-20 pH adjusted, using sodium hydroxide, to 10.0 to 10.8. Water to 1 litre.

To illustrate the hardening effect of the various hardening agents and combinations thereof, eight developers were made up in accordance with the foregoing formulation, but subject to the variations indicated below. Each was used to develop a gelatino silver bromide photographic emulsion at F. for 1 /2 minutes, the developed materials fixed in an ammonium thiosulphate non-hardening fixing bath and washed. The melting point 3 of the gelatin in the fully processed products was determined with the following results:

Developing solution: Melting point, F.

(1) Formula as above but without hardening agents 165 (2) Above formula containing 10. ml./litre diacetyl only (B) 181 (3) Above formula containing 5.12 g./litre 2,3-dihydroxy-1,4-dioxane only (A) 183 (4) Above formula containing 6.7 nil/litre acetouyl acetone only (C) 183 (5) Above formula containing 5.12 g./litre A and ml./litre B. 191 (6) Above formula containing 10 ml./litre B and 6.7 ml./litre C. 196 (7) Above formula containing 5 .12 g./ litre A and 6.7 ml./litre C. 193

(8) Above formula containing 5.12 g./litre A, 10 ml./litre B and 6.7 ml./litre C. above 212 Norm-4n the formula for the developer whenever diacetyl is used extra sulphite must be added to allow for the fol-ma tion of the bisulphite compound.

The film, after processing in developer 8, withstood boiling water for at least /2 hour without any melting or loss of adhesion, and the swollen gelatin remained quite tough throughout. With the developer solutions containing two hardening agents loss of adhesion occurred more or less coincident with the melting point.

Considering these results it can be seen that all the hardening agents, 2,3-dihydroxy-l,4-dioxane, acetonyl acetone and diacetyl, when used alone in a developing solution not to harden the gelatin, also any combination of two such hardening agents acts to harden the gelatin to a greater extent than a single hardening agent, and when all three hardening agents are present a further increase in the hardening of the gelatin is obtained. In order to determine if this was a quantitative elTect or due to an additive action of the three hardeners, further experiments were carried out in which each of the hardening agents was used alone in the developing solution, but double the amount or" hardening agent was used, viz. 10 g./litre 2,3-dihydroxy-1,4-dioxane, ml./litre diacetyl and 13 ml./litre acetonyl acetone, but in every case no increase in the melting point of the gelatin over the figures obtained previously when the smaller quantities of hardening agent were used, was observed.

Therefore it appears that the hardening agent function differently, possibly due to each of the hardening agents preferentially cross-linking at different sites in the gelatin. Hence, to obtain the maximum hardening all three difierent hardening agents must be present in the developing solution.

We claim as our invention:

1. A photographic developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-1,4-dioxane and a source of borate 10115.

2. A photographic developer according to claim 1, wherein 2,3-dihydroxy-1,4-dioxane and the source of borate ions are present in substantially equimolar proportions.

3. A photographic developer according to claim 1,'

6. A photographic developer according to claim 1, of which the pH is 10.0 to 10.8.

7. A photographic developer composition comprising a developing agent for silver halide photographic emulsion at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-1,4-dioxan and a source of borate ions together with a 1,4-diketone which possesses a hardening action on gelatin.

8. A photographic developer composition according to claim 7, wherein the 1,4-diketone is acetonyl actone.

9. A photographic developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-1,4-dioxane and a source of borate ions, together with diacetyl.

10. A photographic developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals 2,3-dihydroxy-l,4-dioxane and a source of borate ions, together with diacetyl and a 1,4-diketone which possesses a hardening action on gelatin.

11. A photographic developer composition according to claim 10, wherein the 1,4-diketone is acetonyl acetone.

12. A method of developing and hardening a photographic silver halide emulsion having a developable latent image which comprises treating the same with a developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkali substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-l,4-dioxane and a source of borate ions.

13. A method of developing and hardening a photographic silver halide emulsion having a developable latent image which comprises treating the same with a developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-1,4 dioxane a source of borate ions together with a 1,4-diketone which possesses a hardening action on gelatin.

14. A method of developing and hardening a photographic silver halide emulsion having a 'developable latent image which comprises treating the same with a developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-1,4-dioxane and a source of borate ions, together with diacetyl.

15. A method of developing and hardening a photographic silver halide emulsion having a developable latent image which comprises treating the same with a developer composition comprising a developing agent for a silver halide photographic emulsion, at least one alkaline substance selected from the class consisting of hydroxides and carbonates of alkali metals, 2,3-dihydroxy-l ,4 dioxane and a source of borate ions, together with diacetyl and a 1,4-diketone which possesses a hardening action on gelatin.

References Cited UNITED STATES PATENTS 2,870,013 l/l959 Jeffreys 96-l.11 X 3,232,761 2/1966 Allen et al. 9666 3,232,764 2/1966 Allen et al. 9666 FOREIGN PATENTS 825,544 12/ 1959 Great Britain.

NORMAN G. TORCHIN, Primary Examiner. R. E. MARTIN, Assistant Examiner. 

